ML20085B521
| ML20085B521 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 05/26/1972 |
| From: | Jewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Bloch E US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20085B488 | List: |
| References | |
| NUDOCS 8307080171 | |
| Download: ML20085B521 (4) | |
Text
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-D) 4 Consumers Power l
mg Company General Offices: 212 West Mechegan Avenue. Jackson, Michegan 49201. Area Code 517 788-OSSO May 26, 1972 Mr. E. J. Bloch, Director Re:
Docket 50-255 I
Directorate of Licensing License No DPR-20 United States Atomic Energy Commission i
i l
Washington, DC 20545
Dear Mr. Bloch:
l This is to apprise you of two incidents which occurred e
recently at the Palisades Plant. The first occurred at 1808 on May 17, 1972 and involved the 1-2 start-up transformer protective relays and the second occurred at 0120 on May 18,1972 and in-volved emergency diesel generator No 1-1.
At the time both of these incidents occurred, the pgant was in a hot standby condition with the primary system at 530 F, 2100 psia and the coolant boron content at refueling concentration.
At 1808 on May 17, 1972, the safety injection system (SIS) test button was pushed to initiate a quarterly test on the left chan-nel of the safety injection system. This resulted in a loss of out-side power as a differential relay on the 2400-volt start-up trans-former operated and cleared the 345 kV "R" bus in the switchyard.
The diesel generator started automatically but required manual synchronization to the 2400-volt safeguard buses 1C and 1D.
This was as designed and due to the test button depression during the auto cycle.
Preparations were made to back feed off-site power through the normal station power transformers while the tripping of the dif-ferential relay was being investigated.
The actuation of the differential relay was spurious and was due to unbalanced sensing currents from the current transformer with load on the start-up transformer. This unbalance was due to the incompatibility of the installed current transformer to the 345 kV to 2.4 kV step-down situation. This unbalance plus the starting currents of the pump motors initiated by the test signal caused the l relay to operate.
8307000171 720712 PDR ADOCK 05000255 S
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Mr. E. J. Bloch 2
Docket 50-255, License No DPR-20 May 26, 1972 At the time the relay operated, the load on start-up trans-former No 1-2 was 4.4 MVA plus the starting current of 1750 horsepower of the motors. From test data and the above load data, the 345 kV current transformers require approximately.8 ampere of excitation current to support the voltage requirement of the current transformer.
With.8 ampere excitation current, the current transformer had 32%
error. The 32% error was enough to cause the differential relay to operate.
To provide protection for start-up transformer No 1-2, the differential relays have been removed and high side overcurrent and instantaneous overcurrent relays have been installed.
The high side overcurrent relays will not trip incorrectly for any current trans-former saturation that occurs.
The protection for start-up transformer No 1-1 was reviewed and the same saturation problem was found to exist for its differen-tial relay. The same changes were made for the No 1-1 transformer as for the No 1-2 transfonner.
The protection for station power transformer No 1-1 and No 1-2 has been reviewed. Current transformer saturation is not considered to be a problem in the application of differential pro-tection to these banks, because of the different voltage ratio of these transformer banks.
The load that existed on the No 1-2 start-up transformer at the time of trip was the maximum expected during plant operation.
The SIS test has been conducted successfully several times before but at the time they were conducted, loads on the transformer were less.
Prior to returning the plant to service, a safety injection system test will be performed which involves simultaneous actuation of both halves of the safety injection system with the plant in a hot standby condition, thereby subjecting the starting power source to the maximum loads they will see.
At 0120 on May 18, 1972, the diesel generator No 1-1 tripped off due to loss of fuel supply. The engine had operated for over seven hours but ran out of fuel as the level switch on the engine fuel res-ervoir failed and prevented the flow of fuel from the day tank.
The level switch which failed and prevented continued op-eration of the diesel generator No 1-1 has been replaced.
In addition, the monthly operational tests on the diesel generator unit have been revised to include a functional check of the level switches which
Mr. E. J. Bloch 3
Docket 50-255, License No DIR-20 May 26, 1972 actuates the fill valve and the low-level alarm. This is accomplished by shutting off the manual valve and allowing the reservoir level to drop until the switches are actuated.
Yours very truly, Ralph B. Sewell (Signed)
RBS/dmb Ralph B. Sewell Nuclear Licensing CC:
- BHGrier, Administrator USAEC l
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UNITED STATES OF AMERICA A.' "v., -
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CONSUMERS POWER COMPANY
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Docket No. 50-255
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CERTIFICATE OF SERVICE Copies of Applicant's WX dated May 26, 1972 from R. B. Sewell to L. D. Low, and letter dated May 26, 1972 from Ralph B. Sewell to E. J. Bloch, have been served upon the following this 1st day of June,1972, by deposit in the United States mail:
Mr. Samuel W. Jensch, Chairman Eric V. Brown, Sr., Esq.
Atomic Safety and Licensing Board Brown, Colman & Dement U. S. Atomic Energy Comnission 125 West Walnut Street Washington, D. C.
20545 Kalamazoo, Michigan 49007 Mr. Warren E. Nyer Myron M. Cherry, Esq.
Idaho Nuclear Corporation 109 N.
Dearborn St.,
Suite 1005 P.O. Box 1845 Chicago, Illinois 60602 Idaho Falls, Idaho 83401 Lewis D. Drain, Esq.
Dr. Clarke Williams Miles, Mika, Meyers, Beckett & Jones Brookhaven National Laboratory 311 Waters Building Upton, L.I., New York 11973 Grand Rapids, Michigan 49502 Mr. Stanley T. Robinson, Jr.
Joseph F. Scinto, Esq.
Chief, Public Proceedings Branch Office of the General Counsel Office of the Secretary of the U. S. Atomic Energy Commission Commission Washington, D. C.
20545 U. S. Atomic Energy Comission Washington, D. C.
20545 Algie A. Wells, Esq., Chairman Atomic Safety and Licensing Appeal Board Nathaniel H. Goodrich, Esq., Chm.
U. S. Atomic Energy Commission Atomic Safety and Licensing Board Washington, D. C.
20545 Panel U. S. Atomic Energy Comission Curtis G. Beck, Esq.
Room 1039 H Street Assistant Attorney General Washington, D. C.
20545 Seven Story Building Lansing, Michigan 48902
/s/ Judd L. Bacon Judd L. Bacon Attorney for Applicant Consumers Power Company 212 West Michigan Avenue Jackson, Michigan 49201 l
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